Improved tensile properties in heterostructured 1050/7050 Al sheets produced by accumulative roll bonding
Danielle Cristina Camilo Magalhães, Osvaldo Mitsuyuki Cintho, Vitor Luiz Sordi, Andréa Madeira Kliauga
Abstract
Tougher and stronger alloys are desired for structural applications, but the strength-ductility trade-off limits it. In order to overcome this issue, heterogeneous structures can be developed in high-strength materials to restore an acceptable ductility for practical use. In this investigation, dissimilar alloys (1050 and 7050 aluminum alloys) were roll bonded at 450 °C and 500 °C to obtain sheets with a heterogeneous structure in terms of microstructure and composition, and the microstructure and tensile properties were investigated. The final microstructure was a combination of soft and coarse-grained 1050 Al layers together with elongated and ultrafine-grained precipitation strengthened 7050 Al layers. A simultaneous increase in strength and ductility was achieved after six cycles at 500 °C with 343 MPa of ultimate tensile strength and ∼14% of uniform elongation, which was associated with the increase in the strain-hardening rate due to the combination of a coarser and ductile microstructure in the 1050 Al layer and a fine grained and precipitation hardened 7050 Al layer. It was also demonstrated that higher interface density in the heterogeneous structure decreased the dynamic recovery rate and a better combination of strength and ductility was achieved. These findings may determine processing parameters to optimize the roll bonding technology and develop new heterostructured sheets for practical applications.